Mission Status Center

A post-scrub statement from the Air Force and ULA has been issued:

"The launch attempt of the United Launch Alliance Delta 4 with the Air Force's Global Positioning System 2F SV-1 satellite (GPS 2F SV-1) has been scrubbed for tonight. Mission managers require additional time to validate the modified approach to monitor the Global Positioning System satellite telemetry signal.

"The Delta 4 rocket and GPS 2F SV-1 satellite are safe and secure at this time. The next launch attempt has been set for Monday with a launch window of 11:13-11:31 p.m. EDT. The weather forecast calls for an 80 percent chance of acceptable weather during the launch window."

SCRUB! The launch team has been instructed to stand down and not proceed with the countdown tonight. The next attempt will made on Monday evening.

The countdown has begun anew for the Delta 4 rocket and GPS 2F-1 spacecraft. The launch team just commenced the Terminal Countdown sequence for tonight's 11:17 p.m. EDT liftoff.

Fueling the rocket with its cryogenic propellants will start in a little while, pending final approval to proceed this evening.

The Delta and GPS teams are gearing up for another shot launching the first spacecraft in the new generation tonight at 11:17 p.m. EDT.

The weather forecast for tonight's launch window now calls for a 90 percent chance of "go" conditions. The outlook predicts scattered low and high clouds, good visibility, northeasterly winds of 8 to 12 knots and a temperature around 75 degrees F.

"Overall pattern influencing Florida will not change over the next couple of days. Combination of surface high pressure to the northeast and low pressure over the eastern Bahamas will provide an easterly flow regime over the region," Air Force meteorologists say.

"Deep layered moisture will be remain limited but may be sufficient to produce an isolated thunderstorm along the east coast sea breeze as it pushes inland and merges with the west coast sea breeze during the afternoon and evening hours. Thunderstorms that do develop will be concentrated over the western half of the Florida peninsula by late afternoon and evening. Persistent easterly flow could result in a few showers developing over the near coastal waters as well.

"There remains a very small threat for a lingering anvil cloud and cumulus clouds to be in the area during the launch window. The Anvil Cloud Rule, Cumulus Cloud Rule and Flight through Precipitation Rule will be the primary concerns for both launch day, and the next day in the event of a 24-hour launch delay."

The debut launch for a new series of Global Positioning System spacecraft is rescheduled for Sunday night from Cape Canaveral, Florida.

The launch team initially prepared to try again Saturday, but officials have decided that Sunday night will be the next try.

"Mission managers expect the telemetry signal issue between the Global Positioning System satellite and the satellite ground support equipment that caused the scrub of Friday's launch attempt to be resolved in time for a launch attempt Sunday," a joint Air Force and ULA press statement says.

Sunday's launch window extends from 11:17 to 11:35 p.m. EDT. Weather forecasters predict a 70 percent chance of good conditions.

A post-scrub statement from the Air Force and ULA has been issued. It cites a telemetry loss as the cause of the countdown hold and scrub. The loss of telemetry was the issue that originally slipped launch to the end of the window, too.

"During the final minutes of the launch countdown, the telemetry signal between the Global Positioning System satellite and the satellite ground support equipment was lost. This issue could not be resolved in time to launch during tonight's 18-minute launch window," the statement reads.

An unspecified technical concern with the Global Positioning System 2F-1 spacecraft stopped the Delta 4 rocket's countdown about four minutes before launch.

Liftoff already slipped from the opening of this evening's launch opportunity at 11:25 to the very end of the window at 11:43 p.m. EDT when the spacecraft team reported a telemetry loss during readiness checks before flight. The issue caused the countdown to remain holding at the planned T-minus 5 minute pause point and a retargeting of liftoff time to the final moment of 18-minute launch window.

All appeared resolved when managers gave approval to resume the countdown and proceed toward an 11:43 p.m. EDT blastoff. But just before clocks reached T-minus 4 minutes, the command was given to stop the countdown because of a spacecraft constraint. No details about the problem were immediately announced.

With no time left in the window to assess the situation, mission managers had no choice but declare an automatic scrub for the night. The Delta 4 rocket will be drained of its cryogenic propellants and safed.

Another launch attempt could come Saturday, when the window will be 11:21 to 11:39 p.m. EDT. Weather forecasters expected a repeat night of favorable conditions.

The launch team has been instructed to prepare for another countdown on Saturday evening.

If another launch attempt is made Saturday, the window would be 11:21 to 11:39 p.m. EDT.

A "no go" condition was declared on the GPS 2F-1 spacecraft, halting the countdown to launch. There is no launch window left tonight to deal with the issue, so this is an automatic scrub for the evening.

HOLD! The countdown has been stopped.

T-minus 4 minutes, 10 seconds. The systems of the first and upper stages of the Delta 4 rocket have switched from ground-fed power to internal batteries for launch.

T-minus 5 minutes and counting! The final phase of today's countdown has commenced for launch of the Delta 4 rocket carrying the GPS 2F-1 navigation satellite. Liftoff is set to occur at 11:43 p.m. EDT (0343 GMT) from pad 37B at Cape Canaveral Air Force Station.

The launch director has given approval to resume the count for liftoff at 11:43 p.m. EDT. The spacecraft issue has been resolved for flight tonight.

A second round of launch team readiness polls and mission managers just occurred. All console operators reported "ready" for liftoff at 11:43 p.m. EDT, including the spacecraft.

The launch team will be re-polled at 11:33 p.m. for a status check.

It's been a very smooth countdown and this last-minute issue with the payload was the first real problem that the launch team has reported all evening.

There's no details on this problem or the odds it can be resolved in the next several minutes. Liftoff must occur by 11:43 p.m. or else wait until tomorrow night.

HOLD EXTENDED. The decision has been made to delay liftoff until 11:43 p.m. EDT, the very end of tonight's launch opportunity, so engineers can assess an issue that arose with the GPS 2F-1 spacecraft.

The final readiness polls of the launch team and mission managers have been completed. A "not ready" was reported due to a spacecraft telemetry issue.

Standing by for the launch team readiness check for continuing the countdown.

The GPS 2F-1 spacecraft atop the Delta 4 has switched from ground-fed power to its internal batteries for launch.

A load relief file based on the upper level winds is being transmitted to the Delta 4 rocket's flight computer. This program informs the rocket on the wind conditions it can expect to see during ascent.

T-minus 5 minutes and holding. The countdown has entered a planned 15-minute hold. This pause is designed to give the launch team the opportunity to catch up on any work running behind schedule and verify all is in readiness for the final moments of the count. A series of management polls will be conducted during the hold to give approval to proceed with the launch.

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The ULA launch team and management are guiding the countdown from the Delta Operations Center, located about 9,200 feet from the pad. The engineers overseeing the rocket and ground systems are located on the third floor and the Mission Directors Center room is on the fourth floor. Both rooms have a view of pad 37B and the Delta 4 rocket out their windows. Other rooms are also set up for engineering support.

The DOC was formerly built to support the Titan-Centaur program but was refurbished to support Delta 4.

The launch weather officer has given his final planned briefing to mission managers in the countdown. Conditions at Cape Canaveral are excellent for a rocket launch tonight.

The outlook for launch time includes just a few low and high clouds, unrestricted visibility, easterly winds of 5 knots and a temperature around 75 degrees F.

T-minus 30 minutes and counting. The countdown is headed to the T-minus 5 minute point where a 15-minute hold is planned. Liftoff is targeted for 11:25 p.m., which is the opening of today's 18-minute launch window.

The latest thermal insulation scans show the vehicle is in good shape for flight tonight.

Now 60 minutes away from the launch of the GPS 2F-1 spacecraft aboard a Delta 4 rocket from Cape Canaveral, Florida. This is the first of a dozen next-generation satellites for the Global Positioning System.

"The 12 GPS 2F satellites will provide improved signals that will enhance the precise global positioning, navigation and timing services supporting both the warfighter and the growing civilian needs of our global economy," said Col. Dave Madden, commander of the Global Positioning Systems Wing at the Space and Missile Systems Center.

"The next-generation satellites will provide improved accuracy through advanced atomic clocks, a longer design life than the previous GPS satellites and a new operational civil signal that benefits aviation safety and search-and-rescue efforts, known as the L5 signal.

"It will also continue to deploy the modernized capabilities that began with the eight modernized GPS 2R satellites, including a more robust and higher power military signal to improve performance and anti-jam resistance.

"GPS has led the charge to improve military and civil navigation capabilities to ensure GPS remains the gold standard for position, navigation and timing service worldwide."

The RS-68 first stage main engine spin start pressurization operation is starting.

The safety checks have been completed satisfactorily.

The safety system checks are beginning at this point in the countdown.

The launch team is entering the last 90 minutes of the countdown. With fueling of the Delta 4 rocket completed, this phase of the count is mostly quiet. Engineers are monitoring systems while the clocks tick down.

In the immediate future, the rocket's safety system will be checked.

Everything continues to proceed on schedule at Cape Canaveral for liftoff at 11:25 p.m. EDT.

Here's a look at some stats about today's mission. This will be:

• The 349th Delta rocket launch since 1960
• The 13th Delta 4 rocket mission since 2002
• The 11th Delta 4 rocket launch from Cape Canaveral
• The 6th Medium+ 4,2 configuration to fly
• The 6th Delta 4 under the ULA banner
• The 2nd Delta 4 launch this year
• The 61st GPS satellite to launch
• The 50th GPS launch on a Delta rocket
• The 1st GPS Block 2F satellite

Radio frequency link checks between tracking facilities at the Cape and the launch vehicle are underway.

The thermal insulation inspections have been completed following fueling. There's a lot of frost around the first stage liquid oxygen feedline elbow, and the team will keep a camera pointed on that area.

Now two hours and counting until launch of the Delta 4 rocket and GPS 2F-1 spacecraft. The launch team is not working any technical issues with the rocket, the vehicle is fully fueled and its cryogenic tanks are conditioned for flight. And the weather conditions look good for a liftoff tonight.

The flight slews and commanding tests for the vehicle steering systems are complete.

Ahead of schedule, the launch team is kicking off the steering checks for the RS-68 main engine and RL10 upper stage engine, plus commanding tests with the solid rocket motors.

You can watch a live video webcast of launch right here on this page. Hit reload on your browser and the video stream will activate. The webcast will play as our text updates automatically refresh for the rest of the countdown and launch.

Engineers are conducting the standard evaluation of the Delta 4 rocket's thermal insulation following the loading of supercold propellants into the vehicle.

Our recap of tonight's Ariane 5 rocket launch from South America can be read here.

The upper stage liquid oxygen filling has been completed. All four of the vehicle's cryogenic tanks are loaded.

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The topping mode is starting for the upper stage's liquid hydrogen tank. The first stage's LOX and LH2 tanks are in topping as well.

The first stage liquid hydrogen tank is now entering the topping phase after standard valve tests.

Now four hours till launch. The Delta 4 rocket's Common Booster Core first stage has been loaded with supercold liquid oxygen and liquid hydrogen. The upper stage filling remains in progress.

Complex 37 has two giant sphere-shaped fuel tanks to store the cryogenic liquid oxygen and liquid hydrogen. The LOX tank holds 250,000 gallons and LH2 sphere about 850,000 gallons. Complex 37 has two giant sphere-shaped fuel tanks to store the cryogenic liquid oxygen and liquid hydrogen. The LOX tank holds 250,000 gallons and LH2 sphere about 850,000 gallons.

The cryogenics are fed from the storage tanks through pipelines to the pad. For the Common Booster Core, the propellants are routed up to the launch table upon which the rocket sits. Tail service masts, the large box-like structures at the base of the vehicle, feed the oxygen and hydrogen to the booster via separate umbilicals.

The upper stage receives its cryos from the middle swing arm that extends from the Fixed Umbilical Tower to the front-side of the rocket.

Upper stage liquid hydrogen tank in fast-fill mode has finished as well. Checks will performed before topping commences.

No issues are being tracked in the countdown and launch remains on target for 11:25 p.m. EDT.

The chilldown of the upper stage liquid oxygen system is reported complete, clearing the way for loading the rocket's tank with 4,500 gallons. This is the last of the rocket's four cryogenic supplies to be filled in today's countdown to launch.

Fast-fill loading of the first stage liquid hydrogen tank has been completed. Vent and relief checks will be performed shortly.

Post-filling tests on the first stage liquid oxygen system are complete. The tank is now entering topping mode.

The "go" has been given for the upper stage liquid oxygen chilldown in advance of fueling.

The launch team is actively loading the upper stage's liquid hydrogen tank with 10,000 gallons of propellant for the RL10 engine.

The chilldown of the upper stage liquid hydrogen system is reported complete, clearing the way for loading the rocket's tank.

Now back at Cape Canaveral, we're just under five hours away from the planned liftoff time for the Delta 4 rocket carrying the first satellite in a new generation for the Global Positioning System. Launch remains on schedule for 11:25 p.m. EDT.

Germany's COMSATBw 2 military communications satellite has been released into orbit by the Ariane 5 rocket, completing tonight's Arianespace launch from Kourou. It was the 194th Ariane rocket to fly and the 50th Ariane 5.

Ariane just deployed the Astra 3B commercial communications satellite. The upper stage will eject its dual-payload adapter hardware before releasing the second spacecraft passenger a short time from now.

The Ariane 5 rocket, which is launching into space right now from South America, just extinguished its cryogenic upper stage engine to completed the powered phase of flight. The stage will prepare for deployment of the two satellite payloads a few minutes from now.

The first stage liquid oxygen loading just finished. The tank has been loaded with its supercold oxidizer that is chilled to Minus-298 degrees F. Topping will be completed as the count rolls on.

The countdown activities are proceeding as planned at Cape Canaveral's Complex 37 for tonight's launch of the Delta 4 rocket with the GPS 2F-1 satellite. Filling of the first stage with liquid oxygen and liquid hydrogen is continuing out at the launch pad, and early preps for the upper stage loading have begun.

Ariane's Vulcain main engine just finished its burn and the core stage jettisoned 107 miles in altitude. The cryogenic upper stage then ignited for its lengthy burn to inject the payloads into a geosynchronous transfer orbit.

And the launch team has gotten the approval to start chilldown conditioning of the upper stage liquid hydrogen system.

Back at Cape Canaveral, first stage liquid hydrogen tanking operation is switching from "slow-fill" to "fast-fill" mode.

Already 45 miles in altitude, Ariane's twin solid rocket boosters have burned out and separated. The cryogenic main stage of the Arianespace vehicle continues to fire.

Meanwhile, an Ariane 5 rocket just blasted off from the Guiana Space Center in Kourou, French Guiana. The launcher is carrying the Astra 3B direct-to-home television and broadband satellite for Europe and COMSATBw 2 communications satellite for the German military.

First stage liquid oxygen loading continues in progress. The rocket will be loaded with 40,000 gallons of supercold LOX.

The start of liquid hydrogen fueling of the first stage is now confirmed. Some 110,000 gallons of LH2 will fill the rocket's tank.

The cold gas chilldown conditioning of the liquid hydrogen system has been accomplished. Liquid hydrogen propellant will begin to flow into the first stage in "slow-fill" mode. That is sped up to "fast-fill" after a small portion of the tank is loaded.

Chilled to Minus-423 degrees Fahrenheit, the liquid hydrogen will be consumed by the RS-68 main engine along with liquid oxygen during the first four minutes of the launch.

First stage liquid oxygen tanking operation is switching from "slow-fill" to "fast-fill" mode.

Everything is going well early in tonight's launch countdown.

The first stage liquid oxygen chilldown is complete. Fueling will begin in the "slow-fill" mode to load a small percentage of the tank. The process then speeds up to the "fast-fill" mode until the tank is nearly full.

The hydrogen system's cold gas chilldown conditioning is officially underway.

A "go" has been given to start the cold gas chilldown conditioning of the first stage liquid hydrogen system.

Chilldown of the first stage liquid oxygen system has begun. This preps the tank and pumping to guard against shock when the supercold oxidizer begins flowing into the rocket a short time from now.

The launch director has given the formal "go" to press ahead with fueling as planned.

T-minus 6 hours, 15 minutes and counting! The Terminal Countdown begins now for today's flight of the United Launch Alliance Delta 4 rocket with the Global Positioning System 2F-1 satellite.

The countdown has one planned built-in hold at T-minus 5 minutes lasting some 15 minutes, leading to liftoff at 11:25 p.m. EDT (0325 GMT).

The launch pad has been verified evacuated of all personnel in advance of fueling the rocket's two stages this afternoon. Pad systems and equipment stand ready for fueling activities, which should kick off shortly.

Check out today's gantry rollback photo gallery taken by ULA's Pat Corkery.

The rocket's avionics have been turned on for launch and the interrogation checks were performed of the C-band beacon used for tracking the vehicle during its flight downrange.

The launch team has been polled to verify all consoles are manned and ready to begin the Terminal Countdown when this hold ends at 4:55 p.m. No technical issues are being worked and the weather looks great.

We've posted a photo gallery of pre-launch shots taken this morning by Spaceflight Now's Stephen Clark at Complex 37.

T-minus 6 hours, 15 minutes and holding. The countdown has just entered a planned 60-minute built-in hold, giving the team time to catch up on any work that could be running behind schedule. Once the clocks resume ticking at 4:55 p.m. EDT, the Terminal Countdown phase of today's launch operation will begin.

Weather forecasters have boosted the odds of acceptable conditions during tonight's window to 90 percent.

The outlook foor launch time includes some scattered low and high clouds, good visibility, easterly winds of 8 to 12 knots and a temperature around 75 degrees F.

"Combination of surface high pressure to the north and developing low pressure over the eastern Bahamas will provide an easterly flow regime over the region. Deep layered moisture will be limited but may be sufficient to produce an isolated thunderstorm along the east coast sea breeze as it pushes inland during the afternoon and evening hours. Thunderstorms will be concentrated over the western half of the Florida Peninsula by late afternoon and evening.

"There is a very small potential for lingering anvil clouds associated with any thunderstorms that do develop to be in the area during the launch window, in addition to cumulus clouds over the near coastal waters. The Anvil Cloud Rule and Cumulus Cloud Rule will be the primary concerns for both launch day, and the next day in the event of a 24-hour launch delay."

The 330-foot tall mobile service tower has been retracted from the Delta 4 rocket at Cape Canaveral's pad 37B for tonight's launch that will place the GPS 2F-1 satellite into Earth orbit.

The wheeled structure just moved along rail tracks to its launch position about the length of a football field away from the rocket. The 9-million pound tower shielded the Delta from the elements during the its stay on the pad, provided workers 360-degree access to the various areas on the vehicle and was used to attach the strap-on solid motors and the payload during the launch campaign. The tower is 90-feet wide and 40-feet deep.

Crews will spend the next couple of hours securing the complex for launch before leaving the danger area around the pad. All workers must be clear of the area for the start of hazardous operations in the countdown, which include fueling the vehicle later this afternoon.

The Terminal Countdown will begin ticking at 4:55 p.m. EDT, leading to the multi-hour process of loading the Delta 4's Common Booster Core first stage and the second stage with supercold liquid oxygen and liquid hydrogen propellants.

Testing of communications links between the rocket and Air Force Eastern Range will occur after fueling is accomplished. Steering checks of the first stage RS-68 engine and second stage RL10 powerplant are on tap in the last hour of the count.

A 15-minute build-in hold is slated for T-minus 5 minutes, during which time teams will go through final polling to grant clearance to launch. The Delta 4 will transition to internal power as the count resumes, ordnance will be armed and the propellant tanks pressurized as clocks target the main engine ignition time at T-minus 5.5 seconds.

Liftoff remains scheduled for 11:25 p.m. EDT, the opening of an 18-minute window that extends to 11:43 p.m. EDT (0325-0343 GMT).

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The first satellite in a new generation for the Global Positioning System, years in the making and built with enhancements users eagerly want, awaits a Friday night blastoff into orbit atop a Delta 4 rocket.

The GPS 2F-1 spacecraft is targeting an 11:25 p.m. EDT launch from Cape Canaveral. An 18-minute window extending to 11:43 p.m. EDT will be available if conditions prevent an on-time liftoff.

We will have extensive live coverage of the countdown and launch on this page.

Weather forecasters are predicting an 80 percent chance of favorable conditions. "There is a small potential for lingering anvil clouds associated with any thunderstorms that do develop to be in the area during the launch window, in addition to cumulus clouds over the near coastal waters," Air Force meteorologists say.

The outlook includes good visibility, northeasterly winds of 10 to 15 knots and a temperature around 75 degrees F.

Boeing developed this satellite and 11 more coming down the pike to sustain and further upgrade the Global Positioning System for the U.S. Air Force.

"These next-generation satellites provide improved accuracy through advanced atomic clocks; a more jam-resistant military signal and a longer design life than earlier GPS satellites; and a new civil signal that benefits aviation safety and search-and-rescue efforts," said Craig Cooning, vice president and general manager at Boeing Space and Intelligence Systems. "GPS 2F is the culmination of our deep experience with 39 successful satellites from previous missions, representing more than 30 years of teamwork with the Air Force."

About three-and-a-half hours after launch, the Delta 4 rocket will deliver the satellite directly to the GPS constellation's altitude 11,000 miles high. Ground controllers expect to have the new bird checked out and ready for use in 90 to 120 days, the Air Force says.

The new GPS 2F-1 spacecraft take over the Plane B, Slot 2 location of the network, considered one of the primary positions in the constellation that is divided into six orbital groupings with multiple satellites flying in each.

The craft will take the current home of the GPS 2A-27 satellite, which was launched in September 1996 and has exceeded its expected lifetime. It will be relocated as part of the Air Force's efforts to spread out the available satellites and increase coverage.

That particular slot was supposed to be occupied by the GPS 2R-20 satellite after it launched in March 2009. But an interference problem with a test payload aboard the craft prevented it from entering service as scheduled.

For more on the GPS 2F program and pre-flight preparations for this new satellite, see our earlier feature story.

The Dela 4 rocket launch has moved to Friday evening, a one-day delay so workers can replace a piece of ground support equipment used to control one of the swing arms on the pad's umbilical tower. The new launch window extends from 11:25 to 11:43 p.m. EDT.

A cadre of military and industry workers at the Cape Canaveral Air Force Station is readying the first-of-its-kind satellite for the Global Positioning System, an advanced bird that will be shipped to the launch pad and bolted atop a Delta 4 rocket next week.

Liftoff of the GPS 2F-1 spacecraft from pad 37B is targeted for May 20 during a launch window extending from 11:29 to 11:48 p.m. EDT.

"We're getting goose bumps right now. We're very excited," said Harry Brown, the GPS 2F program's chief engineer at satellite-builder Boeing.

"There is a pride in working GPS, there is a pride in what we do for the nation and we know this is a national asset."

Read our full story.

The United Launch Alliance Delta 4 rocket that will deploy the first satellite in a new generation of Global Positioning System satellites was placed atop its Cape Canaveral pad Thursday morning.

The bright orange and white launcher is scheduled for blastoff May 20 during a window extending from 11:29 to 11:48 p.m. EDT.

Initial assembly of the rocket, including mating of the cryogenic upper stage to the Common Booster Core first stage using a precision laser alignment system, was completed in the nearby Horizontal Integration Facility.

After a diesel-powered transporter moved the 165-foot-long rocket to the Complex 37 pad, hydraulic pistons beneath the pad's tilt-table lifted the rocket upright at about 10 a.m. EDT Thursday. The vehicle was stood upright within minutes.

Over the coming weeks, a full pre-launch test program will be carried out and the final rocket assembly steps will be completed by attaching the solid-fuel motors to the first stage and mounting the payload aboard.

Read our full story.